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PDF MA828 Data sheet ( Hoja de datos )
| Número de pieza | MA828 | |
| Descripción | 3 Phase / Pulse Width Modulation Waveform Generator | |
| Fabricantes | GEC Plessey Semiconductors | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MA828 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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THIS DOCUMENT IS FOR MAINTENANCE
PURPOSES ONLY AND IS NOT
RECOMMENDED FOR NEW DESIGNS
1 page  
MA828
PWM SWITCHING
INSTANTS
11
TRIANGLE WAVE AT
CARRIER FREQUENCY,
SAMPLING ON 1VE AND 2VE PEAKS
0 POWER WAVEFORM
AS READ FROM
INTERNAL ROM
21
11
RESULTING
PWM
WAVEFORM
0
21
Fig. 3 Asynchronous PWM generation with‘double-edged’ regular sampling as used by the MA828
t1
ALE
RD
t2
WR
t8
CS
AD0-AD7
t10
t15
LATCH ADDRESS
t3
t9
t4
t11
t12
LATCH DATA
Fig. 4 Intel bus timing definitions
Parameter
Symbol Min. Units
ALE high period
t1 70 ns
Delay time, ALE to WR
t2 40 ns
WR low period
t3 200 ns
Delay time,WR high to ALE high t4
40 ns
CS setup time
t8 20 ns
CS hold time
t9 0 ns
Address setup time
t10 30 ns
Address hold time
t15 30 ns
Data setup time
t11 100 ns
Data hold time
t12 30 ns
Table 1 Intel bus timings at VDD = 5V, TAMB = 125°C
t1
AS
t2
DS
R/W
t8
CS
t3
t6
t4
t5
t7
t9
AD0-AD7
t10
t11
t15
LATCH ADDRESS
t12
LATCH DATA
Fig. 5 Motorola bus timing definitions
Parameter
Symbol Min. Units
AS high period
t1 90 ns
Delay time, as low to DS high
t2
40 ns
DS high period
t3 210 ns
Delay time, DS low to AS high
t4
40 ns
DS low period
t5 200 ns
DS high to R/W low setup time t6
10 ns
R/W hold time
t7 10 ns
CS setup time
t8 20 ns
CS hold time
t9 0 ns
Address setup time
t10 30 ns
Address hold time
t15 30 ns
Write data setup time
t11 110 ns
Write data hold time
t12 30 ns
Table 2 Motorola bus timings at VDD = 5V, TAMB = 125°C
4
5 Page 
MA828
HARDWARE INPUT/OUTPUT FUNCTIONS
Set Output Trip (SET TRIP input)
The SET TRIP input is provided separately from the micro-
processor interface in order to allow an external source to
override the microprocessor and provide a rapid shutdown
facility. For example, logic signals from overcurrent sensing
circuitry or the microprocessor ‘watchdog’ might be used to
activate this input.
When the SET TRIP input is taken to a logic high, the output
trip latch is activated. This results in the TRIP output and the six
PWM outputs being latched low immediately. This condition can
only be cleared by applying a reset cycle to the RST input.
It is essential that when not in use SET TRIP is tied low and
isolated from potential sources of noise; on no account should it
be left floating.
SET TRIP is latched internally at the master clock rate in order
to reduce noise sensitivity.
Output Trip Status (TRIP output)
The TRIP output indicates the status of the output trip latch
and is active low.
Reset (RST input)
The RST input performs the following functions when activbe
(low):
1. All PWM outputs are forced low (if not already low) thereby
turning off the drive switches.
2. All internal counters are reset to zero (this corresponds to 0°
for the red phase output).
3. The rising edge of RST reactivates the PWM outputs resetting
the output trip and setting the TRIP output high –
assuming that the SET TRIP input is inactive (i.e. Iow).
Zero Phase Pulses (ZPPR, ZPPY and ZPPB outputs)
The zero phase pulse outputs provide pulses at the same
frequency as the power frequency with a 1 : 2 mark-space ratio.
When in the forward mode of operation the falling edge of ZPPR
corresponds to 0° for the red phase, the falling edge of ZPPY to
0° for the yellow phase and the ZPPB falling edge to 0° for the
blue phase. In the reverse mode, the rising edge of a zero phase
pulse corresponds to 0° for the relevant phase PWM output.
Waveform Sampling Synchronisation (WSS output)
This output provides a square wave signal of 50% duty cycle
at a frequency 1536 times higher than the fundamental of the
power waveform. Each successive pulse of WSS corresponds
to the MA828 reading the next location of the waveform ROM. It
may be used in conjunction with the ZPP signals to monitor the
position of the machine rotor and may form part of a closed loop
control system such as slip compensation.
Clock (CLK input)
The CLK input provides a timing reference used by the
MA828 for all timings related to the PWM outputs. The
microprocessor interface, however, derives all its timings from
the microprocessor and therefore the microprocessor and the
MA828 may be run either from the same or from different clocks.
WAVEFORM DEFINITION
The waveform amplitude data used to construct the PWM
output sequences is read from the internal 38438 ROM. This
contains the 90° span of the waveform as shown in Fig. 18. Each
successive 8-bit sample linearly represents the instantaneous
amplitude of the waveform. It is assumed that the waveform is
symmetrical about the 9o°, 180° and 270° axes. The MA828
reconstructs the full 360° waveform by reading the 0°-90°
section held in ROM and assigning negative values for the
second half of the cycle.
These samples are used to calculate the instantaneous
amplitudes for all three phases, which will be 120° transposed in
the normal R-Y-B orientation for forward rotation or B-Y-R for
reverse rotation. The 384 8-bit samples are regularly spaced
over the 0° to 90° span, giving an angular resolution of
approximately 0·23°.
Waveform segment
Sample number
0°- 30°
0 - 127
30·23°- 60°
128 - 255
60·23°- 89·77°
256 - 383
Table 8 90° of the 360° cycle is divided into 384 8-bit samples
255
VALUE
OF
8-BIT
SAMPLE
POWER
WAVEFORM
0
0° 45° 90°
PHASE (384-BIT RESOLUTION)
Fig. 18 90° sample of typical power waveform
PRODUCT DESIGNATION
Two standard option exist, defining waveform shape. These
are designated MA828-1 and MA828-2 as follows:
MA828-1
Sine1third harmonic at one-sixth the amplitude of the
fundamental:
x(t)
=
A
[sin
(vt)1
1
6
sin
3(vt)]
MA828-2
Pure sinewave:
x(t) = A [sin (vt)]
Additional wave shapes can be implemented to order, provided
they are symmetrical about the 90°, 180° and 270° axes. Contact
your local GEC Plessey Semiconductors Customer Service
Centre for further details.
10
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MA828.PDF ] | |
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